Conventionally, integrated circuits have been mounted on organic or ceramic chip carriers to form electronic modules or packages. The chip carrier provides a mechanical support for the chip as well as electrical interconnection to a printed circuit board. Then, one or more of the electronic modules have been mounted on the printed circuit board to enable electrical communication between the chips and with other circuitry on the board. Two or more of such boards may be installed in a rack to enable electrical communication between the different boards.
Electrical conductors are limited in the rate at which they can propagate electrical signals. This is due to inherent resistance and inductance in the conductors and parallel capacitance caused by adjacent capacitors and other circuitry. Also, for some complex applications, there may not be adequate surface area on the boards for all the conductors that are needed. Also, cross-talk may be a problem for some applications, especially when the conductors are close together and operating at high switching rates.
It was known to mount an integrated circuit on each face of an optical cube to permit the integrated circuits to optically communicate with each other. See for example, U.S. Pat. No. 6,034,821 which describes a two section cube and also mentions a six section cube where each section is a four-sided pyramid. One of the integrated circuits on one face may be a VCSEL which transmits optical signals through the cube. Another of the integrated circuits on another face may be an optical receiver to receive the optical signal transmitted through the cube from the VCSEL. The known optical cubes provide different types of routing of the optical signals. The optical signals can be transmitted straight through the cube to an optical device on a face of the cube opposite to that of the transmitting VCSEL. Alternately, the optical signals can be transmitted partially into the cube and then reflected at ninety degrees by a mirror within the cube. The reflected optical signal can be received by an optical device on a face of the cube which is perpendicular to that of the transmitting VCSEL. The mirror is provided by a reflective, forty five degree internal surface of the cube. Partial mirrors are also known where part of the optical signal passes straight through the partial mirror and the remaining part of the optical signal is reflected at ninety degrees.
The bandwidth of light is much greater than that of an electrical conductor such that these optical communications can occur at a very fast rate. However, there have been some complexities in known optical cubes in bringing electrical signals to and from the chips mounted on the optical cube. Also, there have been some difficulties in known optical cubes in optimizing the throughput of the integrated circuits mounted on the cube.
Accordingly, an object of the present invention is to optimize the throughput of integrated circuits mounted on the optical cube.
Another object of the present invention is to provide a simpler technique to bring electrical signals to and from integrated circuits mounted on the optical cube.